©2005 KEMET Electronics Corp.

May 2005

Product Update – T498 High Temperature (+150°C) Tantalum SMT Capacitors

The tantalum SMT capacitor in its solid-state structure

is typically rated as capable of 125°C applications. The

T498 tantalum surface mount capacitor has a maximum

temperature rating of 150°C. The difference between the

T498 and the standard tantalum capacitors lies within its

material set and design. The materials changed include the

carbon, the silver epoxy, the silver paint, the plastic

molded encapsulant, and the leadframe. These materials

still contain no lead and are fully RoHS

1

compliant. The

standard finish on the leadframe is a matte tin plating over

nickel, and the device is capable of the 260°C reflow pro-

files as defined in J-STD-020C

2

. A gold or tin-lead finish

is also available.

Figure 1. Structure of new T498 tantalum capacitor.

The appearance of this device is radically different

from the previous SMT tantalum capacitors from KEMET,

in that the color is no longer gold with brown lettering.

The gold material has a heat activation of color change

from yellowish gold to brown created in the presence of a

controlled surface temperature rise. A laser flash through

a mask is used to create the polarity and identifying marks

on the gold plastic. Using this material and process in the

presence of higher heats created an effect where the entire

surface of the package was turning brown, and the mark-

ings became indiscernible.

The black compound has no discernable change in col-

oration when exposed to extended temperatures above

125°C. The marking on the package for the polarity stripe,

capacitance code, voltage rating, the KEMET logo, and the

print week code (PWC) are still created with a laser in a

dot matrix pattern. The effect does not create a coloration

change, but creates a surface abrasion as the laser removes

the reflectivity of the plastic surface in the desired pattern.

Figure 2. Photograph of “D” case, T498 SMT capacitors.

Through oblique lighting and vision systems, the mark-

ings can be quite revealing as shown in Figure 2. An ex-

planation for the pattern with the markings is shown in

Figure 3.

Figure 3. Component marking diagram for T498 capacitor.

KEMET Electronics Corp.

P. O. Box 5928

Greenville, SC 29606

(864) 963-6300

www.kemet.com